Disproportionation of olefins

ABSTRACT

Process for the disproportionation of olefins by contacting the olefin with a solid initiator which is the product of reacting a defined organometallic complex of molybdenum, tungsten or rhenium with an inorganic matrix having a hydroxylic surface.

United States Patent Attridge et al.

Apr. 8, 1975 DISPROPORTION ATION OF OLEFINS lnventors: Charles JamesAttridge; Arthur Morris; Hugh Thomas, all of Runcorn. England ImperialChemical Industries Limited, London. England Filed: Jan. 30, 1974 Appl.No.: 437,874

Assignce:

Foreign Application Priority Data [56] References Cited UNITED STATESPATENTS 3.660.369 5/1972 Kormer et al 260/93.l

Primary Examiner-Stanford M. Levin Attorney. Agent, or FirmCushman,Darby & C ushman [57] ABSTRACT Process for the disproportionation ofolefins by contacting the olefin with a solid initiator which is theproduct of reacting a defined organometallic complex of molybdenum,tungsten or rhenium with an inorganic matrix having a hydroxylicsurface.

12 Claims, No Drawings 1 DISPROPORTIONATION or OLEFINS This is adivision of application Ser. No. 236,199 filed Mar. 20, I972, now U.S.Pat. No. 326,199.

This invention relates to the disproportionation of olefins, and also totransition metal compositions suitable as initiators for use in such aprocess in which a transition metal complex is chemically bonded to asubstantially inert matrix material.

It is known that organometallic compounds can be absorbed on inertinorganic materials and the resultant combination used as a heterogenouscatalyst. However. the inorganic material serves merely as a support anddoes not affect the activity of the resultant catalyst.

We have discovered that certain organometallic complexes may bechemically bonded to inorganic matrices, to produce catalytically activecompositions which may be of greater activity than the unmodifiedorganometallic complex.

Our cognate copending British Pat. No. l,3l4.828 describes and claims atransition metal composition which is the product of reacting atransition metal complex of the general formula RIIIMXII with asubstantially inert matrix material having a hydroxylic surface which isfree from adsorbed water, wherein M is a transition metal of Groups IVAto VIA of the Periodic Table of the Elements. R is a hydrocarbon groupor substituted hydrocarbon group, X is a monovalent ligand, and m and pare integers. :11 having a value from 2 to the highest valency of themetal M and p having a value from to 2 less than the valency of themetal M, except when M is a metal of Group VIA when p is always 0.

(All references to the Periodic Table are to the version of the PeriodicTable of the Elements printed inside the back cover of AdvancedInorganic Chemistry" by F. A. Cotton and G. Wilkinson, second Edition,(1966), lnterscience Publishers, New York, London and Sydney).

According to one aspect of the present invention we now provide atransition metal composition which is the product of reacting atransition metal complex of empirical formula with a substantially inertmatrix material having a hydroxylic surface (as hereinafter defined)which is free from adsorbed water, wherein M is a metal of Group VIIA ofthe Periodic Table, R is a hydrocarbon group or substituted hydrocarbongroup, X is a monovalent ligand, and m and p are integers, m having avalue from 2 upto the highest valence of the metal M and p having avalue from O upto 2 less than the valency of the metal M.

Many transition metal complexes exist as dimeric or other oligomericspecies, and it is to be understood that such species are equallyincluded within formula (1) above.

The transition metal is preferably rhenium; and the monovalent ligand Xis preferably an anionic ligand, for example halogen. Hydrocarbon groupsof different types may be associated with a single metal atom.

Suitable hydrocarbon groups R include alkyl and a alkenyl groups(including 'rr-alkenyl groups such as rr-allyl) and substitutedderivatives thereof. A preferred class of organic transition metalcomplexes are those in which some or all of the groups R are groups ofgeneral formula a-bonded to the transition metal through the carbonatom. In this general formula Y may represent an atom or group capableof interaction with the vacant dorbitals of the metal M. Preferably allof the groups R have this formula, but it is possible for some of themto comprise other hydrocarbon groups.

Suitable substituent groups Y include aromatic and polyaromatic groups,for example, phenyl and naphthyl, giving rise, in formula (2) above, tothe aralkyl ligands benzyl and (l-methylene-l-naphthyl) and ringsubstituted derivatives thereof, for example pmethylbenzyl.

Y may also be a cycloalkenyl group, for example. a cyclooctenyl group.

Alternatively, Y may comprise a group of general formula where Zrepresents carbon, silicon, germanium, tin or lead, and each R, whichmay be the same or different represents a hydrocarbon group or hydrogen;but is preferably an alkyl group. Suitable substituent groups Y thusinclude neopentyl and trimethylsilylmethyl; (CH )3CCH;;-flnd By ahydroxylic surface" we mean a plurality of OH groups attached to thesurface of the matrix material, the hydrogen atom of the OH group beingcapable of acting as a proton source, that is, having an acidicfunction. Such a material will be substantially inert in that, whereasthe said Ol-I groups are capable of reacting with, say, the transitionmetal hydrocarbyl complex, the bulk of the matrix material is chemicallyinert. Particularly good examples of such matrix materials are silicaand alumina or mixtures thereof. These comprise a matrix of silicon oralumin ium and oxygen atoms, to the surface of which Oh groups areattached, the hydrogen atoms of said groups having an acidic function.However, apart from the presence of these OH groups, silica and aluminaare generally regarded as chemically inert. Within the terms silica andalumina we include silicaand aluminabased materials containing smallamounts of other suitable inorganic oxides, such as magnesium oxide andzinc oxide.

It is essential that the matrix material is freed from adsorbed water,as this would merely react with and destroy the transition metalcomplex. The matrix materials may be readily freed from such adsorbedwater by, for example, a simple thermal treatment,

The reaction between the transition metal complex and matrix materialcomprises displacement of one or more of the hydrocarbon groups by thehydrogen atom of an OH group or groups, with liberation of thecorresponding free hydrocarbon. The reaction may be represented by thefollowing equation:

wherein M, R. X, m and p have the meanings previously ascribed to themand n is an integer being not more than (m-l It has been found that whenthe defined components of our transition metal compositions are reacted.all except one of the hydrocarbon groups of the organometallic compoundmay be displaced by -OH groups of the matrix. so that there is always atleast one hydrocarbon group attached to the transition metal in theproduct. This appears to be independent of the number of reactablehydroxylic groups present on the surface of the matrix.

The term Matrix (OH represents an inert matrix having at least nreactable hydroxylic groups attached to its surface. The number ofreactable hydroxylic groups, that is. the number available for reaction,will depend on the nature and condition of the matrix material. Forexample, in some materials, because of their molecular configuration.some of the hydroxylic groups present are not reactive under ourconditions. Thus, it is usual to characterise a sample of the matrixmaterial before use, for example. by reaction with an excess of thetransition metal complex or as described below.

The progress of the reaction in the manner indicated in equation (4)above may be readily followed by the evolution of free hydrocarbon RH orby colour changes in the reactants. The fact that the product is achemical entity, not a physical mixture such as a transition metalcomplex physically adsorbed on a granular matrix, may be demonstrated byremoving the product. a coloured, insoluble composition. from thereactants and washing it with a solvent which would remove any adsorbedcomplex from the matrix. When this is done, the complex remains on thematrix. Contrary to this, when our complexes are mixed with an inertmatrix containing no reactable hydroxylic groups, for example silicawhich has been calcined at l200C, although the complex is adsorbed onthe matrix, it is readily removed by washing the product with a solvent.

As previously mentioned, the number of reactable hydroxylic groupspresent in a given weight of matrix will depend upon its nature (forexample, whether it is silica or alumina) and its condition (forexample, its surface area and the treatment it has received to removeadsorbed water). Thus the precise composition of transition metalcompositions according to our invention may vary from one batch orsample to another of the same matrix material; but successive portionsof the same material prepared under identical conditions will giveproducts having the same composition.

Compositions according to the present invention may be prepared bycontacting a solution of the transition metal complex with a suitablematrix material, in the absence of free or adsorbed water. The solventused for the complex should be dry and inert; hydrocarbon solvents arepreferred. Since many of the transition metal complexes which may beused in our process are thermally unstable, the reaction temperaturemust be maintained low enough to avoid decomposition of the complex.With some complexes, temperatures below C are required. Depending on theair-sensitivity of the transition metal complex it may also be necessaryto operate in oxygen-free conditions, for example, under a nitrogenblanket.

The ratio of transition metal complex to matrix material may be variedwithin wide limits depending upon the physical and chemical nature ofthe components used; but it is preferred that the proportions and thenature of the reacting materials, for example, the values of m and p.are so chosen that at least two and preferably at least threehydrocarbon groups remain attached to the transition metal atom in theproduct composition. Preferably, substantially all the hydroxylic groupsof the matrix material are reacted with the transition metal complex.

The matrix material may be characterised in a number of ways. A firstmethod comprises suspending the matrix material, which has previouslybeen freed from water, in an inert liquid, and titrating the reactablehydroxylic groups with a solution of the transition metal complex in aninert solvent. Since most transition metal complexes are stronglycoloured, the end-point is readily detectable by the presence of apermanent colouration in the suspending solvent. ln compositionsprepared in this way, all the reactable hydroxylic groups of the matrixare reacted with the metal complex. The compositions produced may thenbe recovered by filtration from the reaction medium, freed from solventand stored dry or under solvent in oxygen-free I conditions.

It is possible, if desired, to add less than the complete titre oftransition metal complex, or even to add excess transition metalcomplex. but when excess complex is used, it will remain in the reactionmedium when the composition is separated.

A second method for preparing compositions according to our inventioncomprises, first, characterising a sample of the material by addingexcess of an organometallic transition metal complex (which may or maynot have the formula 1) above) or a Grignard reagent (magnesiumhydrocarbyl halide) to a sample of the matrix material and determiningthe number of molecules of hydrocarbon liberated from a known amount ofmatrix material; and secondly, adding to a further portion of the matrixmaterial just sufficient of the desired transition metal complex toliberate an appropriate amount of hydrocarbon. For example, a sample ofthe matrix material may be suspended in a solvent and excess of atransition metal 1r-allylic compound added. The volume of propyleneproduced is measured and related to the weight of matrix material. Asecond sample of the matrix material is then taken and the appropriatetransition metal qr-allylic complex added until the volume of propyleneproduced per gram of matrix material present is equivalent to thatpreviously determined by addition of excess transition metal complex.

As already mentioned, the compositions may be separated from the mediain which they are produced and exist as chemical entities of definitecomposition. In many cases they are more thermally stable than thetransition metal complexes from which they are produced.

Compositions prepared as described above may have useful catalyticactivity. For example, rheniumcontaining compositions may be used asreforming catalysts for petroleum hydrocarbon.

According to another aspect of the present invention, we provide aprocess for the disproportionation of olefinically unsaturatedhydrocarbons in which the olefinically unsaturated hydrocarbon iscontacted with an initiator which is the product of reacting atransition metal complex of empirical formula with a substantially inertmatrix material having a hydroxylic surface which is free from adsorbedwater. as described above or in the Complete Specification of ourcognate copending British Patent Application No. 40416/69 and 40417/69.wherein M is molybdenum, tungsten or rhenium. R is a hydrocarbon groupor a substituted hydrocarbon group. X is a monovalent ligand and m and pare integers, m having a value from 2 upto the highest valence of themetal M and 2 having a value from 0 upto 2 less than the valence of themetal M.

As described above, the monovalent ligand X is preferably an anionicligand. for example halogen. and the groups R may be the same ordifferent.

Suitable hydrocarbon groups R include alkyl and alkenyl groups(including rr-alkenyl groups such as rr-allyl) and substitutedderivatives thereof. A preferred class of organic transition metalcomplexes are those in which some or all of the groups R are groups ofgeneral formula %-bonded to the transition metal through the carbonatom. In this general formula Y may represent an atom or group capableof interaction with the vacant D- orbitals of the metal M. Preferablyall of the groups R have this formula, but it is possible for some ofthem to comprise other hydrocarbon groups.

Suitable substituent groups Y include aromatic and polyaromatic groups,for example, phenyl and naththyl, giving rise, in formula (2) above. tothe aralkyl ligands benzyl and (l-methylene-l-naphthyl) and ringsubstituted derivatives thereof, for example p-methylbenzyl. Y may alsobe a cycloalkenyl group, for example, a cycloocentenyl group.

Alternatively, Y may comprise a group of general formulakis-(trimethylsilymethyl) tungsten or molybdenum,

and hexakis(trimethylsilylmethyl)dimolybdenum.

Particularly when molybdenum and rhenium complexes of formula (5) aboveare employed in the production of the initiator, it is preferred thatthe transition metal complex is an oligomeric. for example dimericspecies, as in tetrakis(-rr-allyl)dimolybdenum orhexakis(1r-allyl)dirhenium.

lt is also preferred that the values of m and p are such that at leastthree groups R remain attached to the metal atom M in the initiatorcomposition.

Conveniently. the initiator is employed in a finely divided form. e.g.particles. granules. pellets or the like.

Since the transition metal complexes are often airor water-sensitive, itis preferred to operate under anhydrous and oxygen-free conditions. forexample by drying all solvents used in the preparation of the initiatoror in the disproportionation reaction and by operating under anoxygen-free atmosphere. For example nitrogen or the reactant gases.

By disproportionation" is meant a reaction between two olefinicallyunsaturated molecules with cleavage of the double bonds andrecombination of the resultant fragments to form different olefinicallyunsaturated materials.

Such a reaction commonly gives more than one product, but in all casesthe sum of the number of carbon atoms of the products equals the sum ofthe number of carbon atoms of the reactants.

Disproportionation may occur between two molecules of the same material,when two products are normally produced. one of higher molecular weightthan the starting material and one of lower molecular weight. Forexample, butene can give a mixture of C- C olefins and hexene a mixtureof C- ,-C olefins. Alternatively, molecules of two different materialsmay react, as for example, in the reaction of but-l-ene and pent-2-eneto give propylene and hex-3-ene.

The term olefinically unsaturated hydrocarbon is intended to includeboth mono-olefins, for example ethylene, propylene, butenes, pentenesand hexenes, and polyenes, for example butadiene.

Alternatively, cyclic olefins. for example cyclopentene or norbornene(bicyclo[2.2.l ]hept-Z-ene) may be employed as starting material.Disproportionation in such a case involves ring opening at the olefinicdouble bond and recombination of the resultant fragments. This processmay occur repetitively to produce polymeric materials; for exampledisproportionation of cyclopentene produces a linear, rubberypolypentenamer.

The reaction is carried out by contacting the olefinically unsaturatedhydrocarbon with the initiator.

The starting materials may be liquid. or gaseous under the conditions ofreaction. The starting materials may be dissolved in a suitable inertsolvent or diluent. for example a paraffinic hydrocarbon, but it ispreferred to operate in the absence of solvent.

The reaction may be carried out as a batch process in a suitable vessel,preferably with agitation of the contents to ensure intimate contact ofthe reactants and the initiator.

Alternatively, the reactants may be caused to flow past the initiator.The reactants may be caused to percolate through a fixed bed ofinitiator, or the initiator particles may be suspended in a movingstream of the reactants. Preferably, the initiator particles are causedto flow in countercurrent fashion to the moving stream of reactants.

Alternatively. the initiator may be employed as a fluidised bed.Preferably, a gaseous reactant is used to induce fluidisation of theinitiator particles.

Temperature and pressure of reaction are not critical. It is preferredto operate at ambient pressure, but particularly with gaseous reactants,higher pressures may be employed. The temperature of reaction willdepend of the desired reaction rate, but it is to be noted that highertemperatures commonly favour the production of products of higher carbonnumber. It will be appreciated that isomerisation of starting materialor initial products may occur as determined by the thermodynamics of thesystem. and this tendency may be increased by increased contact timesover the catalyst.

On completion of reaction, materials may be sepa rated from the catalystby conventional means, for example decantation or filtration. ifdesired, individual reaction products may be separated from each otheror from unreacted starting materials, for example by distillation.

Particularly when the initiator is employed in aliquid suspension, itmay be desirable to increase the surface area of the initiatorcomposition by subjecting it to a comminution procedure, for example bysubjecting a suspension of the initiator to ultrasonic dispersion.

The invention is now illustrated by the following Examples. In all theExamples, transition metal complexes and compositions containing themwere prepared and handled under an atmosphere of dry, oxygen-freenitrogen or, where appropriate, were blanketed with the olefinundergoing reaction. All solvents and diluents were dried bydistillation from sodium wire, and were deoxygenated before use. Theproducts of disproportionation reactions were analyzed by gas-liquidchromatography.

PREPARATION OF TRANSITION METAL COMPLEXES Example I Preparation ofMolybdenumallyl Molybdenum pentachloride was dissolved in diethyl ether.and equivalents of an etheral solution of allylmagnesium chloride wereadded dropwise at ambient temperature, while the mixture was stirredvigorously.

On completion of reaction, the deep green solution was filtered toremove magnesium chloride, and the ether was stripped off in vacuo. Theresidue was extracted with the minimum quantity of dry, deoxygenatedpentane to give a deep green solution which was shown by infra-redspectroscopy to contain tetrakis(1rallyl) molybdenum and the dimericspecies tetrakis(1rallyl)dimolybdenum. For reasons of convenience,thismixture will be referred to as molybdenum'allyF.

The tetrakis(rr-allyl) molybdenum could be purified, if required, byfractional crystallisation.

Example 2- Preparation of Tetrakis(1r-allyl) Molybdenum An etheralsolution of molybdenum pentachloride was added dropwise over a period of3 hours to a stirred solution of allyl magnesium chloride intetrahydrofuran at 60C until the molar ratio of molybdenum pentachlorideto Grignard reagent was 0.l8;1. The

mixture was evaporated to dryness in vacuo and the residue was extractedwith pentane at ambient temperature to give a yellow solution. Thissolution was concentrated, and held at -40C overnight when yellowcrystals of tetrakis(1r-allyl)molybdenum separated out. These werepurified by sublimation at 60-65C and 1 torr pressure, and identified byinfra-red spectroscopy.

Example 3 Preparation of Tetrakis(1r-allyl)dimolybdenumTetrakis(rr-allyl)dimolybdenum (molybdenum 1r-allyl dimer) was preparedaccording to the method described and claimed in our copending BritishPatent Application No. 30266/71.

dimolybdenum tetra-acetate was suspended in dry, degassed, diethyl etherin the proportion of 200 mole per litre. The suspension was blanketedwith nitrogen and 900 mole of allyl magnesium chloride were added perlitre of suspension, as a 0.45 M solution in diethyl ether. The mixturewas stirred at ambient temperature for about 1.5-2.5 hours until all thesolid material had dissolved and the solution was a dark green colour.

The solution was evaporated to dryness and the resultant green residuewas extracted four times with pentane to give a pale green solution oftetrakis(1rallyl)dimolybdenum, which was identified by infra-redspectroscopy.

Example 4 Preparation of Tetrakis(rr-crotyl) dimolybdenumTetrakis('n'-crotyl) dimolybdenum was prepared by.

the method described and claimed in our copending British PatentApplication No. 30266/71.

Dimolybdenum tetra-acetate was suspended in dry, deoxygenated diethylether in the proportion of 311 mole per litre.

The suspension was added dropwise over a period of 1 hour to a stirredetheral solution of crotyl magnesium bromide at 0C, until the molarratio of dimolybdenum tetra-acetate to Grignard reagent was 115.36.

Stirring was continued until all the dimolybdenum tetra-acetate haddissolved, and the resultant green solution was evaporated to dryness.the residue was extracted with dry, deoxygenated pentane at 40C to givea dark green solution which is believed to betetrakis(1r-crotyl)dimolybdenurn.

Example 5 Preparation of Tetrakis(1r-ailyl) tungsten Solid tungstenhexachloride was added over a period of 2 hours to a stirred solution oflithium ally] in diethyl ether/tetrahydrofuran at ambient temperature,until the molar ratio of tungsten hexachloride to lithium allyl was 1:8.The resultant brown mixture was stirred for another hour and thesolvents were removed in vacuo at ambient temperature.

The brown residue was extracted with pentane at 40C to give a pale brownsolution from which pale brown crystals of tetrakis(1r-allyl)tungstencould be recovered; These were purified by sublimation at 75C and apressure of 1 torr, and identified by infra-red spectroscopy.

Example 6 Preparation of rhenium Ir-allyl Anhydrous rheniumpentachloride was dissolved in pure, anhydrous diethyl ether to give anorange-red solution.

The solution was cooled to 70C and 5 equivalents of an etheral solutionof allylmagnesium chloride were added while the reaction mixture wasstirred.

After complete addition of the allylmagnesium chloride, the mixture waswarmed to 40C and allowed to stand for 12 hours. A green solution wasobtained.

stirred solution of lithium allyl in tetrahydrofuran at 60C until themolar ratio of rhenium pentachloride to lithium allyl was 1:7. The brownmixture was stirred for another hour and the solvents were removed invacuo.

The brown residue was extracted with pentane to yield a brown solution.This was evaporated to dryness. and the resultant solid product sublimedat 75C and a pressure of 0.1 torr to give a yellow oilv A mass spectrumof this oil gave a parent ion at m/e 302, with a Re, Cl isotope patternindicative of bis(allyl)rhenium chloride.

Example 8 Preparation of hexakis(1'r-ally1)dirheniumHexakis(1r-al1y1)dirhenium (rhenium 1T-allyl dimer) was preparedaccording to the method described and claimed in our copending BritishPatent Application No. 30266/71.

Dichlorodirheniumtetra-acetate was. suspended in dry diethyl ether inthe porportion of 50 mole per litre. The reaction vessel was purged withnitrogen, and 350 mole of allyl magnesium chloride per litre ofsuspension were added slowly, as a 0.14 M solution in diethyl ether. Thecontents of the reaction vessel were stirred during addition of theallyl magnesium chloride. The yellow-orange suspension was immediatelyconverted to a deep red-brown solution.

After 1 hour at ambient temperature, the reaction mixture was evaporatedto dryness while holding the temperature below C. The solid residue wasextracted three times with dry, deoxygenated pentane, at a temperaturebelow 0C, to give a deep red-brown solutiori ofhexakis(rr-allyl)dirhenium, which was identified by infra-redspectroscopy and mass spectral analysis. This solution was stored undernitrogen at a temperature below 40C.

Preparation of Initiator Compositions 1n the following Examples, theappropriate matrix material was dried in vacuo (10' torr) as describedin the Examples and was then cooled under dry nitrogen. The dry materialwas suspended in the minimum quantity of dry, deoxygenated pentane andthe suspension titrated with a pentane solution of the appropriatetransition metal complex, prepared as in Examples 1-8, until a permanentcolouration remained in the suspending solvent. The coated compositionwas recovered by filtration, washed with pentane and dried in vacuo.

Alternatively, the initiator could be employed as a suspension inpentane.

Example 9 Molybdenum allyl/allumina with but-l-ene 60-80 mesh BSS'y-alumina (Koninklijke Zwavelzuurfabrieken v/h Ketjen N. V. Grade CK300 was dried at 500C for 12 hours and reacted with molybdenum allyl".

The product, which was coloured brown and contained 1.3% by weight ofmolybdenum, was placed in a dry flow reactor in an atmosphere of dry,oxygen-free nitrogen. But-l-ene, which had been deoxygenated and driedby passing it over freshly prepared, support copper turnings (BTSCatalyst) and molecular sieve (type 5A) was passed through the catalystbed at 25C for 12 hours, at a velocity calculated to give a contact timeof 12 seconds.

The effluent gas contained C -C olefins, the aver age butene conversionbeing 2%.

Conversion could be temporarily increased to 6% by increasing thereactor temperature to C.

Progressive increases in reactor temperature temporarily increasedcatalyst activity, and also altered the product distribution towards thehigher carbon numbers.

At 200C, product olefins ranged from C to C and, also, substantialisomerisation to but-2ene was occurring.

Example 10 Molybdenum ally1/silica with hex-1ene Silica (Manosil GradeVN3) was dried at 500C for 12 hours and reacted with molybdenum allyl.

The coated silica, which contained 0.077% by weight of molybdenum, waspacked in a column, and 15 times its weight of hex-l-ene vapour, atreflux temperature, was passed through the column over a period of 4hours.

apart from butene, the effluent contained decene (46%), nonene (12%),octene (2%), heptene (13%), and unreacted hex-1-ene (27% Example 11Molybdenum allyl/alumina with norbornene y-Alumina (Grade CK 300) wasdried at 500C for 24 hours and was reacted with molybdenum allyl. Theproduct contained 0.32% by weight of molybdenum.

The initiator was mixed with five times its weight of norbornene and themixture was heated to C for 2 hours.

The initiator was removed by filtration, and methanol added to thefiltrate to precipitate a rubbery polymer.

Evaporation of the solvents after precipitation of the polymer left asweet-smelling yellow oil, which was shown by analysis to be a mixtureof oligomers of norbornene.

Example 12 Tetrakishr-allyl)molybdenum/silica gel with hex-l-ene Silicagel (Davison Chemical Co. Grade 952) was dried at 650C for 12 hours andwas reacted with tet rakis('rr-al1y1)molybdenum. The product wasyellowbrown, and contained 1.1% by weight of molybdenum.

Hex-l-ene was added to the initiator, in the proportion of 20 dm per kg,and the mixture was stirred at ambient temperature for 20 hours.

At the end of this time, 67% of the hexene had reacted; 35% to deceneand ethylene, 18% to heptene and pentene, 1 1% to nonene and propylene,and 3% to octene and butene.

Example 13 Tetrakis(1r-allyl)molybdenum/silica gel with hex-l-ene Theprocedure of Example 12 was repeated, except the silica gel was dried at200C for 12 hours. The coated silica gel was brown and contained 1.5% byweight of molybdenum.

After 1 hour reaction at 60C. 20% of the hexene had been convertedalmost exclusively to decene and ethylene.

Example 14 Molybdenum rr-allyl dimer/alumina with hexl-ene y-Alumina(Grade CK 300) was dried at 500C for 12 hours and reacted withmolybdenum rr-allyl dimer.

The product, which was coloured black and contained 2.4% by weight ofmolybdenum. was placed in a round-bottomed flask, together with timesits own weight of hex-l-ene. Ethylene was evolved on contact of thehexene with the catalyst compositon at ambient temperature.

The flask contents were heated to 35C for 4 hours. At the end of thisperiod. analysis of the flask contents showed that 25% of the hexene hadbeen converted to ethylene and decene.

Example 15 Molybdenum rr-allyl dimer/alumina with hex-l-ene Theprocedure of Example 14 was repeated at a temperature 35C for 24 hoursfollowed by a period of 4 hours at reflux temperature.

The conversion of hex-l-ene to ethylene and decene was 75%. ln addition.about 10% of the product olefins were derived from isomers of hex-l-ene.

Example 16 Molbydenum rr-allyl dimer/alumina with hex-l-ene Example 17Molybdenum 'rr-allyl dimer/silica gel with hexl-ene Silica gel (Grade952) was dried at 650C for 12 hours and reacted withtetrakis(1r-allyl)dimolybdenum. The product was a very dark green blackand contained 3 by weight of molybdenum.

Hex-l-ene was added to the initiator, in the proportion of drn per kg.and the mixture was stirred at 60C for 4 hours.

20% of the hexene was converted almost exclusively to decene andethylene.

Example 18 Molybdenum rr-allyl dimer/silica gel with hexl-ene Theprocedure of Example 17 was repeated, except that the silica gel wasdried at 200C. The coated silica gel was deep maroon and contained 3.5%by weight of molybdenum.

After 15 hours reaction at 60C, 35% of the hexene was converted almostexclusively into decene and ethylene.

Example 19 Molybdenum 'rr-allyl dimer/alumina with hept-3-ene y-Aluminawas dried at 500C and reacted with molybdenum 1r-ally1 dimer. Theproduct was dark-black and contained 2.3% by weight of molybdenum.

Hept-3-ene was added to the initiator, in the proportion of 10 drn perkg, and the mixture was allowed to stand at ambient temperature for 18hours.

14% of the heptene reacted; 10% to decenes and butenes, 3% to octenesand hexenes, and 1% to nonenes and pentenes.

Example 20 -Molybdenum rr-allyl dimer/alumina with 3,3-dimethylbutene-ly-Alumina was dried at 500C and reacted with molybdenum 'rr-allyl dimer.The product was dark brownblack and contained 2.3% by weight ofmolybdenum.

3.3-Dimethylbutene-l was added to the initiator, in the proportion of 10drn per kg, and the mixture was allowed to stand at ambient temperaturefor 24 hours. 16% of the dimethylbutene was converted to a mixture of Colefins.

Example 21 Molybdenum 1r-allyl dimer/alumina with cyclopenteneir-Alumina (Grade CK 300) was dried at 500C for 24 hours and was coatedwith molybdenum 1r-allyl dimer. The product contained 2.4% by weight ofmolybdenum.

The initiator was charged to a stainless steel autoclave, together withcyclopentene, in a weight ratio of 4.6:35. The mixture was stirred atambient temperature and autogenous pressure for 5 hours and was thenallowed to stand for 2 days.

The resultant clear, viscous liquid was washed from the initiator withbenzene and was evaporated to dryness to yield a rubber-like polymer.This was shown by infra-red spectroscopy to be a polypentenamer -(-CH CHCH CH=CH)-,,, with cis and trans forms in the ratio of 47:53.

The conversion of cyclopentene to polymer was 12%.

Example 22 Tetrakis(1r-crotyl)dimolybdenum/alumina with hexl -eney-Alumina pellets were dried at 500C and reacted with tetrakis(rr-crotyl)dimolybdenum. The product was a dark chocolate-brown andcontained 1.3% by weight of molybdenum.

The initiator was mixed with hex-l-ene (10 dm of hexene/3 kg of alumina)and the mixture was stirred at 20C for 2 hours. At this end of thisperiod 6.5% of the hexene had reacted; 4.2% to decenes and ethylene,1.3% to nonenes and propylene, and the remainder to octenes, heptenes,pentenes and butenes.

Example 23 Tetrakis(1r-allyl)tungsten/alumina with hex-l-ene 'y-Alumina(Grade CK 300) was dried at 500C for 12 hours and reacted withtetrakis(n'-allyl) tungsten. The product contained 0.8% by weight oftungsten.

The initiator was placed in a round-bottomed flask, together withhex-l-ene, in a weight ratio of 3:10. Evolution of ethylene occurred oncontact of the hexene with the catalyst composition at ambienttemperature.

The flask contents were heated to 35C for 8 hours. At the end of thisperiod, the conversion of hex-l-ene to ethylene and decene was 25%.

Example 24 Tetrakis(1r-allyl)tungsten/alumina with hex-l-ene Theprocedure of Example 23 was repcatd at a temperature of 35C for 24hours. followed by a period of s 6 hours at reflux temperature.

Conversion of hex-l-ene to ethylene and decene was 70%. In addition.about of the product olefins were derived from isomers of hex-l-ene.

Example 25 Rhenium ar-allyl/alumina with hex-l-cne y-Alumina (Grade CK300) was dried at 500C for l hour and reacted with rhenium rr-allyl. Theproduct was a pale brown Hex-l-ene was refluxed with the initiator forseveral hours to give dec-S-ene.

Example 26 Bis(allyl)rhenium chloride/alumina with hex-l-ene y-Aluminawas dried at 500C and reacted with bis- (allyl) rhenium chloride. Theproduct was pale brown and contained 5% by weight of rhenium.

Hex-l-ene was added to the initiator at ambient temperature. in theproportion of 4 dm per kg. A vigorous evolution of ethylene occurredimmediately.

After 2 hours reaction at ambient temperature. 57% of the hexene wasconverted almost exclusively to decene and ethylene.

Example 27 Bis(allyl)rhenium chloride/alumina with cyclopenteney-Alumina was dried at 500C and was reacted with bis(allyl) rheniumchloride. The product was pale brown and contained 5% by weight ofrhenium.

A solution of cyclopentene in toluene (5.66M) was stirred with theinitiator for 24 hours at embient temperature, in the proportion of dmper kg.

5% of the cyclopentene was converted to yellow elastomeric material.

Example 28 Rhenium 1r-allyl dimer/alumina with hex-l-ene y-Alumina wasdried at 500C for 3 hours and was reacted with rhenium 'zr-allyl dimer.The product was brown.

The initiator was mixed at ambient temperature with dry degassedhex-l-ene (4 dm of hexene per kg of alumina). lmmediate'evolution ofethylene occurred.

After 2 hours reaction. 14% of the hexene was converted to dec-S-ene.

What we claim is:

l. A process for the disproportionation of olefinically unsaturatedcyclic hydrocarbons in which the olefinically unsaturated cyclichydrocarbon is contacted with an initiator which is the product ofreacting under anhydrous and oxygen-free conditions a transition metalcomplex of empirical formula R,,,MX,,

with a substantially inert inorganic oxide matrix material having ahydroxylic surface which is free from adsorbed water and which iscapable of reacting with the transition metal complex. wherein M ismolybdenum. tungsten or rhenium. R is a hydrocarbon group or asubstituted hydrocarbon group, X is a monovalent ligand and m and p areintegers. m having a value of from 2 up to the highest valence of themetal M and having -a value from 0 up to 2 less than the valence of themetal 2. A process as claimed in claim 1 in which the groups R. whichmay be the same or different. are each alkyl or alkenyl or groups ofgeneral formula CH Y a-bonded to the transition metal through the carbonatom. where Y is an atom or group capable of interaction with the vacantd-orbitals of the metal M or is a group of general formula ZR where Z iscarbon. silicon, germanium. tin or lead and each R. which may be thesame or different. is a hydrocarbon group or hydrogen.

3. A process as claimed in claim 1 in which the groups R are rr-allyl.benzyl. p-methylbenzyl. l-methylene-l-naphthyl. neopentyl ortrimethylsilylmethyl.

4. A process as claimed in claim 2 in which the transition metal complexis tetrakis(All) tungsten or molybdenum. tetrakis(All) dimolybdenum.hexakis(All) dirhenium. tris(All) tungsten halide. or tris( All)molybdenum halide. where (All) is 1r-allyl. 1r-methallyl. or 'rr-crotyl,molybdenum or tungsten tetrabenzyl. tris(- benzyl) tungsten halide. trisbenzyl molybdenum halide. tetrakis(p-methylbenzyl) molybdenum ortungsten. tetrakis-( l-methylene-l-naphthyl) molybdenum or tungsten.tetrakis(trimethylsilylmethyl) molybdenum or tungsten. orhexakis(trimethylsilylmethyl) dimolybdenum.

5. A process as claimed in claim 1 in which the values of m and p aresuch that at least three groups R remain attached to the metal atom M inthe initiator composition.

6. A process as claimed in claim 1 in which the transition metal complexis an oligomeric (including dimeric) species.

7. A process as claimed in claim 1 in which the matrix material issilica or alumina.

8. A process as claimed in claim 1 in which substantially all thereactable hydroxylic groups of the matrix have been reacted with thetransition metal complex.

9. A process as claimed in claim 1 when performed in the absence ofsolvent for the olefinically unsaturated hydrocarbon.

10. A process as claimed in claim 1 in which the olefinicallyunsaturated hydrocarbon is caused to flow past the initiator.

11. A process as claimed in claim 1 in which. before use, a suspensionof the initiator is subjected to an ultrasonic dispersion procedure.

12. A process as claimed in claim 1 in which the olefinicallyunsaturated cyclic hydrocarbon is norbornene or cyclopentene.

1. A PROCESS FOR THE DISPROPORTIONATION OF OLEFINICALLY UNSATURATEDCYCLIC HYDROCARBONS IN WHICH THE OLEFINICALLY UNSATURATED CYCLICHYDROCARBON IS CONTACTED WITH AN INITIATOR WHICH IS THE PRODUCT OFREACTING UNDER ANHYDROUS AND OXYGEN-FREE CONDITIONS A TRANSITION METALCOMPLEX OF EMPIRICAL FORMULA
 2. A process as claimed in claim 1 in whichthe groups R, which may be the same or different, are each alkyl oralkenyl or groups of general formula --CH.sub.2 Y .alpha.-bonded to thetransition metal through the carbon atom, where Y is an atom or groupcapable of interaction with the vacant d-orbitals of the metal M or is agroup of general formula ZR.sub.3.sup.1, where Z is carbon, silicon,germanium, tin or lead and each R.sup.1, which may be the same ordifferent, is a hydrocarbon group or hydrogen.
 3. A process as claimedin claim 1 in which the groups R are .pi.-allyl, benzyl, p-methylbenzyl,1-methylene-1-naphthyl, neopentyl or trimethylsilylmethyl.
 4. A processas claimed in claim 2 in which the transition metal complex istetrakis(All) tungsten or molybdenum, tetrakis(All) dimolybdenum,hexakis(All) dirhenium, tris(All) tungsten halide, or tris(All)molybdenum halide, where (All) is .pi.-allyl, .pi.-methallyl, or.pi.-crotyl, molybdenum or tungsten tetrabenzyl, tris(benzyl) tungstenhalide, tris benzyl molybdenum halide, tetrakis(p-methylbenzyl)molybdenum or tungsten, tetrakis-(1-methylene-1-naphthyl) molybdenum ortungsten, tetrakis(trimethylsilylmethyl) molybdenum or tungsten, orhexakis(trimethylsilylmethyl) dimolybdenum.
 5. A process as claimed inclaim 1 in which the values of m and p are such that at least threegroups R remain attached to the metal atom M in the initiatorcomposition.
 6. A process as claimed in claim 1 in which the transitionmetal complex is an oligomeric (including dimeric) species.
 7. A processas claimed in claim 1 in which the matrix material is silica or alumina.8. A process as claimed in claim 1 in which substantially all thereactable hydroxylic groups of the matrix have been reacted with thetransition metal complex.
 9. A process as claimed in claim 1 whenperformed in the absence of solvent for the olefinically unsaturatedhydrocarbon.
 10. A process as claimed in claim 1 in which theolefinically unsaturated hydrocarbon is caused to flow past theinitiator.
 11. A process as claimed in claim 1 in which, before use, asuspension of the initiator is subjected to an ultrasonic dispersionprocedure.
 12. A process as claimed in claim 1 in which the olefinicallyunsaturated cyclic hydrocarbon is norbornene or cyclopentene.